Blood samples are drawn routinely from patients for use in numerous types of blood tests. The blood needed for many tests is conventionally drawn by creating a small incision in the patient's skin. Typically, such incisions are made on the patient's fingertip, however, with such patients as neonates or persons with poor circulation, the incision can be made in alternate areas such as the foot, arm, leg, etc. Typically, the device used to create the needed incision in the patient is a mechanical lancet device. Such lancet devices conventionally employ a cutting blade spring loaded within a housing. The housing is placed against a patient's skin and the blade is released. The potential energy stored within the spring bias of the blade then causes the blade to exit the housing and to create the needed incision in the patient's skin. The advantages of such mechanical lancet devices is that uniform incisions can be made providing good control over the location, depth and sterility of the incision. Furthermore, such mechanical lancet devices often prevent the patient from seeing the often unsettling scene of his or her skin actually being cut.
In the development of the art for mechanical lancet devices, many different designs have been created. The most modern of the designs typically are disposable, having retractable blades and other operations that prevent their reuse after a single incision has been made. Another common feature to many prior art lancet devices is that they made incisions using a plunge cut, that is the cutting blade is plunged through the skin traveling perpendicular to the skin and the size of the incision matches the size of the cutting blade. In U.S. Pat. No. 5,133,730 issued on Jul. 28, 1992 to Biro, entitled DISPOSABLE RETRACTABLE FINGER STICK DEVICE AND METHOD FOR MAKING THE SAME and assigned to International Technidyne Corporation the assignee herein, a sharp blade on a pivot arm is spring biased to move out of and then reenter a housing via an orifice in the housing to incise a patient's skin. Although, the blade is positioned on a pivot arm the blade is directed into the skin of the patient relatively perpendicular to the surface of the skin. The shape of the blade helps the blade enter the skin and make the needed incision.
Lancet devices that create plunge cut are exemplified by U.S. Pat. No. 3,760,809 to Cambell, Jr. entitled SURGICAL LANCET HAVING CASING and U.S. Pat. No. 4,553,541 to Burns entitled AUTOMATIC RETRACTABLE LANCET ASSEMBLY. In both references, the blades are plunged into the skin at an angle substantially perpendicular to the skin. When creating an incision for obtaining a blood sample, it is desirable to create a fairly deep cut so that a good blood flow will result from the incision. However, when using certain prior art lancet devices of the type that utilize a downward thrust to provide a cut pointed blades are typically used to facilitate the cut. Pointed blades create a V-shaped incision down through the skin of the patient. Consequently, the widest region of the incision is on the surface of the skin, while the narrowest region of the incision coincides the deepest point of the incision. Since the narrowest point of the cut is also the deepest point of the cut, a relatively deep incision must be made to ensure enough capillaries are severed to achieve the necessary bleeding.
Another disadvantage associated with plunge cut lancet devices is that they are painful. As will be recognized by any person skilled in the art, a plunge incision is more traumatic than an incision made by a scalpel slice. As such, there is less pain associated with a slice incision than with a plunge incision. Slice incisions as indicated are less intrusive and heal more readily. Additionally, incisions produced by the above-noted prior art devices are made by a downward thrust into the skin. As such, there may be a problem of excessive force being applied to the skin, which can cause skin tissue surrounding the incision to be damaged. Generally, only a small amount of downward force is required to make the incision. However, when the operator actuates the device, his hand may exert an additional, and often excessive, downward force. Thus, the guillotine-like, vertical thrust of the blade, coupled with excessive downward force exerted by the operator may cause damage to the skin and cause skin tissue juices to mix with blood, thereby producing improper blood samples. In general, most plunge type lancet devices depend on spring force for incision and retraction and are often unreliable in the accuracy and repeatability of the depth of the cut due to the wide range of skin toughness encountered in normal populations.
In the prior art, slice action devices are typically used to implement incisions which permit the observation of the bleeding times, wherein bleeding time is defined as the time between implementing the incision and the moment when the bleeding stops. Such slice action devices are exemplified by U.S. Pat. No. 4,064,817 to Reno, entitled DEVICE FOR MAKING PRECISE INCISIONS FOR BLEEDING TIME TESTING AND THE LIKE and U.S. Pat. No. 4,157,086 to Maiorano et al. entitled APPARATUS FOR IMPLEMENTING A STANDARDIZED SKIN INCISION. In both references, blades are causes to slice across a patient's skin causing a elongated incision. The disadvantages of the Maiorano and Reno references is that they both create cuts that are much longer than they are deep. As such, the resulting cut is inappropriate for use on a fingertip or other body part with a small surface area. Furthermore, both the Maiorano and Reno references disclose reusable devices which presents a sterility problem and a hazard of contamination to patients.
The "APPARATUS FOR IMPLEMENTING A STANDARDIZED SKIN INCISION" disclosed in U.S. Pat. No. 4,643,189, and issued to Michael Mintz, and assigned to the assignee herein shows a slice action cutter that creates a rectangular incision. The Mintz patent includes a housing having an internal hollow and a base containing an elongated slot. The internal hollow contains a moveable pivot arm having a blade extending form one end. The pivotal movement of the pivot arm is controlled by a cam having three distinct shaped sections. The cam controls the path of the cutting edge as it implements the incision. As the pivot arm follows the cam, the three distinctly shaped regions of the cam cause the cutting blade to exit the housing, create the incision and return into the housing, respectively. The incision created is rectilinear thereby creating an optimal incision for a bleed time test. The cut provided is implemented by the blade first depending from the slot and plunging into the skin and then traversing the skin and then retracting from the skin back into the housing.
It is, therefore, an objective of the present invention to provide a disposable, single-use lancet that utilizes a slicing action, wherein a short deep incision can be affected on a patient's fingertip or another body part with a reduction in both trauma and pain incurred in the patient as a result of the incision.